1. Field of the Invention
This invention generally relates to a pressure source for a pressure device comprising a pump for pumping fluid from a fluid tank, an accumulator connected to the pump and to the pressure device, a pressure detecting means for detecting the pressure in the accumulator, and a controller for controlling the operation of the pump in an ON-OFF manner on the basis of a result of detection by the pressure detecting means.
2. Description of the Prior Art
Such a pressure source for a pressure device is conventionally used in a hydraulic braking pressure controlling device disclosed, for example, in Japanese Patent Application Laid-open No. 279449/90, and there are two types of such prior art pressure source which control the operation of the pump in an ON-OFF manner. One of them (a) is to control the operation of the pump on the basis of a detection value provided by a single pressure detecting means for detecting the pressure in the accumulator, and the other type (b) is to control the operation of the pump on the basis of results of calculation of a detection value provided by the pressure detecting means, an electric current value of a motor, a wheel speed and the like in a processing circuit including a microcomputer.
However, the prior art pressure source of the type (a) does not have a function to emit an alarm when a trouble occurs, nor a function to stop the operation of the system in response to the trouble and hence, such prior art pressure source is not functionally satisfactory. Further, in the prior art pressure source of the type (b), a trouble may occur in the processing circuit and hence, it is necessary to provide a proper back-up measure. Moreover, in both the pressure sources of the types (a) and (b), the pressure detecting means is single and therefore, it is necessary to further provide a measure for the case when the pressure detecting means breaks down.